Radiotherapy in gastric cancer

Dr.Mina TajvidiRadiation oncologist

NeoadjuvantAdjuvantCurativePalliative

Neoadjuvant Radiation therapy

the results of a phase III study from Beijing demonstrated a survival benefit for patients with gastric cardia carcinoma receiving preoperative irradiation and surgery versus surgery only

Neoadjuvant Radiation therapy

Since preoperative radiation therapy and chemotherapy have improved the surgical outcome in patients with rectal and esophageal cancer, this is a logical approach to explore in gastric cancer as well.

Neoadjuvant Radiation therapy

Although no phase III trials have tested the value of preoperative radiation plus chemotherapy for patients with gastric cancer, two phase III trials for patients with esophagus cancer have included either lesions of the gastric cardia (143) or the esophagogastric junction (84). In both trials, the trimodality arm demonstrated an improvement in survival when compared with the control arm of surgery alone.Preoperative chemoradiation data for patients with gastric cancer is limited to phase II

Neoadjuvant Radiation therapy

Preliminary uncontrolled data suggest that with preoperative combined modality therapy (chemoradiotherapy with or without induction chemotherapy), approximately 70 percent of patients with localized but initially unresectable gastric cancer can undergo potentially curative resection, with pathologically complete response rates as high as 30 percentAlthough these early data seem encouraging, the studies have been conducted in highly selected patients, and randomized trials will ultimately be necessary to confirm benefit from any of these approaches over chemoradiotherapy alone.

Adjuvant Therapy 80 percent of patients who die from gastric cancer experience a local recurrence at some time in their illness The term adjuvant therapy is best used to describe additional treatment in an attempt to increase cure rates in patients who have already undergone a potentially curative resectionFor gastric cancer, an R0 surgical procedure, in which all gross disease has been removed, the margins of resection are microscopically negative, and no distant metastases were found, is required before adjuvant therapy is consideredResections that leave microscopic or gross residual disease are not adjuvant treatment, but rather therapy of known residual cancer

Adjuvant Therapypatients with early stage gastric cancers (e.g., AJCC stage 1A) have a good to excellent chance of cure with surgery alonepatients with more advanced stages, even if all visible disease has been resected with negative microscopical margins, have a far worse outcome

Adjuvant TherapyClinical studies performed in the past not infrequently allowed a delay of up to eight to 12 weeks after operation before beginning Adjuvant TherapyRelatively few studies have evaluated radiation therapy alone (with no concomitant chemotherapy) as an adjuvant to surgical resection of gastric cancer

Adjuvant radiotherapy improved the overall survival no survival advantage other radiation approaches have been tried including intraoperative electron beam radiation therapypatients receive a single dose of high-energy electrons delivered to the tumor bed at the time of gastrectomy [improved 5-year survival (20%) in patients with locally advanced disease ]

Adjuvant TherapyMost of the studies that have evaluated radiation therapy as an adjuvant have used concomitant 5-FU chemotherapy

Radiation for Palliationno studies have evaluated the use of radiation therapy in patients with locally recurrent or metastatic carcinoma of the stomachIts use is likely to be limited to palliation of symptoms such as bleeding or controlling pain secondary to local tumor infiltration

Technique of Radiation TherapyGenerally gastric radiation therapy emphasizes anteroposterior-posteroanterior fields as this minimizes the total volume of normal tissue that is irradiatedIntensity modulated radiation techniques and split field techniques are at times very useful in obtaining an improved dose distribution.Generally a dose of 45 Gy given at 1.8 Gy/d has a low chance of producing significant late complicationsAt doses higher than 50 Gy, the risk of late complications increases, and these doses should be limited to very small volumes in those who are at high risk for recurrence.

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